High-voltage electrical switchgear is used to control, protect, and isolate electrical equipment providing power to premises such as office buildings, hospitals, warehouses, data centers, factories, retail establishments, shopping malls, schools, multi-unit dwellings, government buildings, and embassies, to name a few examples. Typically, in an enclosed building, the high-voltage switchgear is contained in one or more cabinets located in a secure electrical room. Depending on the voltage levels involved, the switchgear may be located in an electrical substation or in an outdoor staging area. The high-voltage switchgear includes programmable logic controllers (PLC) configured to control one or more cabinets, and each cabinet may include high-voltage, high-current power conducting elements such as circuit breakers, fuses, switches, lightning arrestors, and other components used to energize and de-energize the switchgear to allow work to be performed and clear faults downstream.
Switchgear can be dangerous, and accidents can, and do occur. This is especially true, for example, when the high-voltage equipment is re-energized. During re-energization of the equipment, if an abnormal condition develops, which may be caused by poor design, a stray object or tool being dropped inside the cabinet, by faulty wiring, or by a ground-fault, a large electrical arc or an explosion may be produced. Such an electrical arc can be lethal many feet away, and depending on the power levels involved, could be potentially lethal to anyone within the entire electrical room. A large electrical arc may be produced even at lower voltages, such as 480 volts.
As a result, safety procedures are used to protect technicians performing maintenance work as well as other individuals who might be in the proximity of the maintenance work and thus at risk of harm. These safety procedures are often specified by safety organizations such as Underwriters Laboratories (UL) and in some cases required by local regulations and/or electrical codes. In many places, only certain qualified technicians (e.g. trained and certified electricians) can be present when one of the electrical switchgear cabinets is opened up for maintenance. The technicians performing the maintenance work are required to wear protective gloves, glasses, hard hats, or other safety gear.
At the same time, traditionally, lighting in high voltage rooms was often poor and typically uncontrolled. Such room lighting was not sufficient for the technician to comfortably see inside the cabinet once the cabinet door is opened during the time that a technician may be performing repairs or maintenance. Recently, smart lighting systems have been proposed. One such system is described in U.S. patent application Ser. No. 15/833,087, filed on Dec. 6, 2017, entitled, “Sensing and Alert System for Electrical Switchgear,” which discloses a sensing and alert system with time of flight (ToF) sensors and lighting modules installed inside each switchgear cabinet. As one of the safety features provided by the sensing and alert system, the lighting module illuminates an inside portion of the cabinet in response to the ToF sensor detecting that the cabinet door was opened.